On 12/06/2011 09:07 AM, Thierry Reding wrote: > Hi, > > I'm working on adding support for a device which is booted from a device tree > only. Currently this gets me to a login prompt on a serial console and the > device is basically functional. However, the device also has a display with a > backlight that is controlled via a PWM (supplied by the SoC). If this was a > regular board it would be simple to implement this via the pwm-backlight > driver. > > Unfortunately, the pwm-backlight driver doesn't have device tree support yet > and I'm not sure how to best implement it. As far as I can see, I would first > need to have some way of representing a PWM device in the DT that I could > reference in the pwm-backlight device node and I would need to add actual DT > support to pwm-backlight. Implementing support for the data passed in the > platform data should be rather straightforward, but I don't see how the > callback functions could be represented in the DT. > > For some setups it would probably be enough to just specify the used PWM, but > other boards fiddle with some GPIOs in the callbacks and I guess that could > be represented by adding a "gpios" property with a list of pins that need to > be toggled for example when the backlight power is enabled/disabled. > > Has anyone done something similar yet? Am I even on the right track here? >
I haven't seen anything. Perhaps something similar to how the gpio-keys binding is done would work here. This could have a phandle to the pwm device similar to gpios. Rob _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
